Airborne Microbial Communities Research Articles

Impact of climate zones and seasons on indoor airborne microbial communities: Insights from a comprehensive analysis

Bacteria and fungi are ubiquitous throughout built environments and are suspended in the air, potentially affecting human health. However, the impacts of climate zones on the diversity, structure, and stochastic assembly of indoor airborne microbes remain unknown. This study comprehensively analyzed indoor airborne microbes across five climate zones in China during the summer and winter using high-throughput sequencing. The diversity and structure of indoor airborne communities vary across climatic zones. A random forest model was used to identify biomarkers in different climate zones. The results showed no relationship between the biomarkers and their rankings in mean relative abundance. The Sloan neutral model fitting results indicated that the impact of climate zones on the stochastic process in the assembly of indoor airborne microbes was considerably more important than that of seasons. Additionally, the influence of seasons on the diversity, structure, and stochastic assembly process of indoor airborne microbes differed among different climate zones. The diversity, structure, and stochastic assembly processes of bacteria present distinctive outcomes in climate zones and seasons compared with those of fungi. Overall, these findings indicate that customized strategies are necessary to manage indoor airborne microbial communities in each climate zone, season, and for specific microbial species.

Ocular mucosal homeostasis of teleost fish provides insight into the coevolution between microbiome and mucosal immunity

BackgroundThe visual organ plays a crucial role in sensing environmental information. However, its mucosal surfaces are constantly exposed to selective pressures from aquatic or airborne pathogens and microbial communities. Although few studies have characterized the conjunctival-associated lymphoid tissue (CALT) in the ocular mucosa (OM) of birds and mammals, little is known regarding the evolutionary origins and functions of immune defense and microbiota homeostasis of the OM in the early vertebrates.ResultsOur study characterized the structure of the OM microbial ecosystem in rainbow trout (Oncorhynchus mykiss) and confirmed for the first time the presence of a diffuse mucosal-associated lymphoid tissue (MALT) in fish OM. Moreover, the microbial communities residing on the ocular mucosal surface contribute to shaping its immune environment. Interestingly, following IHNV infection, we observed robust immune responses, significant tissue damage, and microbial dysbiosis in the trout OM, particularly in the fornix conjunctiva (FC), which is characterized by the increase of pathobionts and a reduction of beneficial taxa in the relative abundance in OM. Critically, we identified a significant correlation between viral-induced immune responses and microbiome homeostasis in the OM, underscoring its key role in mucosal immunity and microbiota homeostasis.ConclusionsOur findings suggest that immune defense and microbiota homeostasis in OM occurred concurrently in early vertebrate species, shedding light on the coevolution between microbiota and mucosal immunity.1WNPLmNTzstteMxSNP_LzTVideo

Metagenomic and Machine Learning Meta-Analyses Characterize Airborne Resistome Features and Their Hosts in China Megacities.

Urban ambient air contains a cocktail of antibiotic resistance genes (ARGs) emitted from various anthropogenic sites. However, what is largely unknown is whether the airborne ARGs exhibit site-specificity or their pathogenic hosts persistently exist in the air. Here, by retrieving 1.2 Tb metagenomic sequences (n = 136), we examined the airborne ARGs from hospitals, municipal wastewater treatment plants (WWTPs) and landfills, public transit centers, and urban sites located in seven of China's megacities. As validated by the multiple machine learning-based classification and optimization, ARGs' site-specificity was found to be the most apparent in hospital air, with featured resistances to clinical-used rifamycin and (glyco)peptides, whereas the more environmentally prevalent ARGs (e.g., resistance to sulfonamide and tetracycline) were identified being more specific to the nonclinical ambient air settings. Nearly all metagenome-assembled genomes (MAGs) that possessed the site-featured resistances were identified as pathogenic taxa, which occupied the upper-representative niches in all the neutrally distributed airborne microbial community (P < 0.01, m = 0.22-0.50, R2 = 0.41-0.86). These niche-favored putative resistant pathogens highlighted the enduring antibiotic resistance hazards in the studied urban air. These findings are critical, albeit the least appreciated until our study, to gauge the airborne dimension of resistomes' features and fates in urban atmospheric environments.

107 Abundance and Diversity of Microbial Community in Bioaerosol Samples Taken from a French Cheese Dairy

Abstract Bioaerosol samples were taken at a cheese company producing about ten different products. The aims were (i) to investigate airborne microbial community (quantity/diversity) using molecular analytical methods and (ii) to appreciate how molecular methods improve the characterization of bioaerosols. Ambient bioaerosol samples were performed using 37-mm 3-pieces closed-face polypropylene cassettes equipped with 0.8 µm pore size polycarbonate membrane at 2 or 10 L.min-1, in several work areas during winter and summer seasons. Airborne bacteria and fungi were quantified by counting colonies on culture media and by quantitative PCR (qPCR). The microbial community was identified using 16SrRNA and ITS1 genes high-throughput sequencing with sequence analysis performed on the Galaxy Migale platform using the FROGS data processing pipeline. The results showed that ambient concentration levels were working area dependent. A massive emission of microorganisms into the air was found in areas in which a brushing task of cheeses was performed, leading to high concentrations of cultivable (up to 107 CFU/m3) and total (up to 1010 18SrRNA copies/m3) fungi. The correlation between cultivable and total mold is discussed and individual exposures are evoked. The microbial community was characterized by the predominance of the fungal genus Penicillium and their species composition depended on the type of cheese or season. This work has shed new light on these still poorly documented work situations and is essential to refine the diagnosis of the immunoallergic risks of the workers concerned. The presentation discusses the complementarity between culture-based and molecular-based methods for the assessment of bioaerosols.

Airborne microbiomes at a subtropical island in southern China: Importance of the northwest and southeast monsoons

Airborne microbes can survive in the atmosphere, travel intercontinental distances by air mass movement, and colonize in remote area through dry and wet deposition, thus forming a connection between oceanic, atmospheric, and terrestrial systems. However, studies linking the monsoon and bioaerosol transport are extremely rare. Here we applied high-throughput sequencing to investigate airborne microbial community succession on an island in Pearl River Estuary under summer and winter monsoon influence. The microbial communities from local potential sources (i.e., soil, leaf and surface seawater), water-soluble ions, organic carbon and elemental carbon were used to evaluate marine and terrestrial contribution. Our results revealed that airborne microbial communities underwent rapid changes during different monsoons influence (ANOSIM, P < 0.005), especially fungal aerosol. Fungal aerosols were dominant by Cladosporium, Debaryomyces, Rhodotorula, Fusarium, Aureobasidium and Candida during winter monsoon, while Coriolopsis, Ceriporia, Fomes, Phanerochaete, Trametes, Phlebia, and Antrodia were predominant fungal genera during summer monsoon. Redundant analysis showed that changes of air temperature and relative humidity caused by monsoon were the most important driven factors of airborne microbial communities in summer monsoon for airborne microbial communities. In addition, terrestrial sources were the most important contribution, especially that of soil for airborne bacteria. Some taxa were affected by atmospheric transport influenced by monsoon synoptic air mass movement.

What Is Going on in Indoor Air Quality of a University Hospital in Northern Cyprus?

There are two main purposes of microbial monitoring of the inanimate hospital environment. One of them is to monitor hygiene standards, and the second is to determine the presence of nosocomial pathogens. This study was aimed to investigate the indoor environment of the different departments of a university hospital. The prospective study was conducted in a university hospital, a teaching hospital with 143 beds and 30 ICU beds, and a hospital with 6 different wards in Northern Cyprus. Active air sampling was done by using an air IDEAL 3P device. Air samples were taken at 38 points defined before in different parts of the hospital. Our results showed a low level of microorganisms' numbers in microbial airborne communities in a university hospital. Moreover, our results indicated that the temperature of the hospital's indoor environment is not significantly related to the airborne microbial community. On the other hand, our results indicate that the Aspergillus species were mostly isolated in the drug preparation room. The studies have shown that one of the causes of hospital infections is the microorganisms entering the airborne microbial communities. In this case, epidemiology and pathogenesis of airborne microbial communities should be understood.

Vertical distribution of airborne microorganisms over forest environments: A potential source of ice-nucleating bioaerosols

Airborne microorganisms transported from forested areas can influence cloud formation by forming ice nuclei. However, the vertical transportation of airborne microorganisms over forested areas is not well understood. We collected aerosols at three heights, [ground (2 m), canopy top (20 m), and above canopy (500 m)] during the summer, fall and winter, to analyze the airborne microbial communities that were distributed vertically over the forest. During summer and fall, the microbial particles maintained similar concentrations in the forest zone (canopy top and ground) and decreased to 1/10th of the microbial concentration in the above canopy area. The particle concentrations in winter indicated efficient vertical mixing below 500 m. High-throughput DNA sequencing revealed that the airborne microbial communities were composed of terrestrial and phyllospheric species associated with the degradation of decaying plant litters. Regardless of the three seasons, the above canopy was dominated by atmospheric stress-resistant bacteria from the phyla Actinobacteria and Firmicutes. Unlike bacteria, the mushroom-type fungal members of Agaricomycetes grew in relative abundance above the canopy, primarily throughout the summer and winter, while mold-type fungal Dothideomycetes species were often found at all three heights during the fall. The Fusarium, Pseudomonas, and Bacillus isolates, which were obtained from air samples at three heights, indicated high activities of ice nucleation in the water-drop freezing assay. Therefore, ice-nucleating microbial taxa likely originated from fungal and bacterial communities in the soil litter and plant surfaces of the phyllospheric environments.

Fog-Induced Alteration in Airborne Microbial Community: a Study over Central Indo-Gangetic Plain in India.

Fog supports an increase in airborne microbial loading by providing water with nutrients and protecting it from harmful incoming solar radiation. To improve our present understanding of fog-induced alteration in an atmospheric microbial community, a study was conducted during 1 to 14 January 2021 for continuous investigation of airborne bacteria over a rural site, Arthauli (25.95°N, 85.10°E), in central Indo-Gangetic Plain (IGP) in India. An increase of 36% ± 0.4% in airborne bacterial loading was noticed under fog versus prefog conditions, and a decrease of 48% ± 0.4% was noticed under the postfog condition. Airborne bacterial loading had a strong correlation with RH (R2 = 0.56; P < 0.05), temperature (R2 = -0.55, P < 0.05), and wind speed (R2 = -0.52, P < 0.05). Unique types of bacteria, representing about 29% of the whole community, were detected only under foggy conditions, likely by a continuous supply of nutrients and water from a cold, calm, and humid atmosphere. As a result, no significant diurnal variation of bacterial loading was noticed on a foggy day, with a higher daily mean concentration of about (8.4 ± 1.7) × 105 cells · m-3 than that on a typical winter day [(6.3 ± 3.8) × 105 cells · m-3]. A typical winter day experienced about a 60% decrease in bacterial loading in the afternoon in comparison to that in the morning. A 3-day back-trajectory analysis suggests a slow movement of airmass along with the wind blowing from west to central IGP. Fog pauses wind movement, which reduces continuous transportation of urban sources while increasing airborne bacteria from local sources. The abundances of Gp6 (14.8% ± 8.6%), Anaeromyxobacter (7.1% ± 2.8%), and Gp7 (6.8 ± 2.6%) have been observed to increase due to occurrences of fog over central IGP. IMPORTANCE Fog was investigated in the present study as a cause of alteration in the airborne microbial community. Occurrences of fog were responsible for an increase in airborne microbial loading (36%) over central IGP in India due to the easy availability of nutrients and water in the air and dimming of harmful solar radiation. More than 90% of unique bacteria were detected under fog (64%) and postfog (28%) conditions. A few bacteria, like Gp18 (0.5% ± 0.3%), Alicyclobacillus (0.5% ± 0.1%), Sinomonas (0.4% ± 0.2%), and Phenylobacterium (0.4% ± 0.2%), were detected only under foggy conditions. A strong correlation between meteorological parameters and bacterial loading was found in the current research work. The present study provides additional support toward a new direction in interdisciplinary science for the detailed investigations of the effects of meteorological conditions on airborne bacteria and their implications for society.

Analysis of the composition of culturable airborne microorganisms in the archaeological excavation protection site of the Nanhai No. 1 Ancient Shipwreck.

After the recovery of the ship from the sea on 2007, the Nanhai No. 1 Ancient Shipwreck is currently exposed to the air. Air microorganisms settle on wooden shipwrecks, and they can use wood matrix to grow and multiply, causing biocorrosion and biodegradation. In this study, a systematical survey of the composition of culturable airborne microorganisms was performed at the conservation site of the Nanhai No. 1 Ancient Shipwreck. Airborne microorganisms were collected from seven sites in the preservation Nanhai No. 1 area over five periods. Molecular identification of the culturable microorganisms isolated from the air was done by sequencing both 16S rRNA (bacteria) and ITS (fungi) gene regions. The biodegradability of these strains was evaluated by degradation experiments with cellulose and lignin as substrate. The results showed that the composition of the isolated microbial communities was different in each period, and microbial spatial distribution was dissimilar in the same period. In the recent 2020, the dominant bacterial genus was Acinetobacter, and the dominant fungal genera were Penicillium, Aspergillus, and Cerrena. Acinetobacter spp. can degrade cellulose and lignin. Penicillium spp., Aspergillus spp., and Cerrena spp. degraded cellulose but only Cerrena spp. could utilize lignin. These dominant strains may have a harmful effect on the Nanhai No. 1 Ancient Shipwreck. This study provides data on the airborne microbial community found inside the protective chamber where Nanhai No. 1 Shipereck is placed, which can be used as a reference basis for the future conservation of the ship.

Short-range contributions of local sources to ambient air.

Recent developments in aerobiology have enabled the investigation of airborne biomass with high temporal and taxonomic resolution. In this study, we assess the contributions of local sources to ambient air within a 160,000 m2 tropical avian park (AP). We sequenced and analyzed 120 air samples from seven locations situated 160 to 400 m apart, representing distinct microhabitats. Each microhabitat contained a characteristic air microbiome, defined by the abundance and richness of its airborne microbial community members, supported by both, PCoA and Random Forest analysis. Each outdoor microhabitat contained 1% to 18.6% location-specific taxa, while a core microbiome of 27.1% of the total taxa was shared. To identify and assess local sources, we compared the AP dataset with a DVE reference dataset from a location 2 km away, collected during a year-round sampling campaign. Intersection of data from the two sites demonstrated 61.6% of airborne species originated from local sources of the AP, 34.5% from ambient air background, and only 3.9% of species were specific to the DVE reference site. In-depth taxonomic analysis demonstrated association of bacteria-dominated air microbiomes with indoor spaces, while fungi-dominated airborne microbial biomass was predominant in outdoor settings with ample vegetation. The approach presented here demonstrates an ability to identify local source contributions against an ambient air background, despite the prevailing mixing of air masses caused by atmospheric turbulences.

Seasonal taxonomic composition of microbial communal shaping the bioaerosols milieu of the urban city of Lanzhou.

Here, the taxonomical composition and seasonal dynamics of airborne microbial communities were described in the urban city of Lanzhou, Northwest China. Year-long samples were studied in two filter membranes (Quartz and PTFE). Higher microbial loads were reported in the PTFE than in the quartz filter. Onefold decrease was reported in bacterial loads in spring and summer than winter and autumn for both filters. The fungal loadings were lowest during winter and highest during autumn, followed by summer. The microbial communities included Actinobacteria and Proteobacteria, Ascomycota, and Basidiomycota as major components. Maximum abundance of the members from Gammaproteobacteria, Coriobacteria and Clostridia were studied in all seasons on PTFE membrane, followed by, Erysipelotrichia, Negativicutes and Fusobacteria. Members of Actinobacteria and Bacilli showed higher abundance in spring and winter, with a small proportion during autumn. Members of Clostridia, Gammaproteobacteria, Bacilli, and Actinobacteria showed maximum abundance on the quartz filter in all the seasons. Similarly, on the PTFE, fungi including Dothideomycetes and Agaricomycetes were dominant, followed by Saccharomycetes during summer and winter. The result showed that PM2.5, SO42-, NO2-, Na+, EC, and OC are important environmental parameters influencing the seasonal microbial community. However, the relation of the microbiome with the environment cannot be confidently defined because the environmental factors are changeable and yet interrelated.

Airborne microbial community structure and potential pathogen identification across the PM size fractions and seasons in the urban atmosphere

As a vital component of airborne bioaerosols, bacteria and fungi seriously endanger human health as pathogens and allergens. However, comprehensive effects of environmental variables on airborne microbial community structures remain poorly understood across the PM sizes and seasons. We collected atmospheric PM1.0, PM2.5, and PM10 samples in Hefei, a typical rapidly-developing city in East China, across three seasons, and performed a comprehensive analysis of airborne microbial community structures using qPCR and high-throughput sequencing. Overall the bacterial and fungal abundances in PM1.0 were one to two orders of magnitude higher than those in PM2.5 and PM10 across seasons, but their α-diversity tended to increase from PM1.0 to PM10. The bacterial gene abundances showed a strong positive correlation (P < 0.05) with atmospheric SO2 and NO2 concentrations and air quality index. The bacterial gene abundances were significantly higher (P = 0.001) than fungi, and the bacterial diversity showed stronger seasonality. The PM sizes influenced distribution patterns for airborne microbial communities within the same season. Source-tracking analysis indicated that soils, plants, human and animal feces represented important sources of airborne bacteria with a total relative abundance of more than 60% in summer, but total abundance from the unidentified sources surpassed in fall and winter. Total 10 potential bacterial and 12 potential fungal pathogens were identified at the species level with the highest relative abundances in summer, and their abundances increased with the PM sizes. Together, our results indicated that a complex set of environmental factors, including water-soluble ions in PM, changes in air pollutant levels and meteorological conditions, and shifts in the relative importance of available microbial sources, acted to control the seasonal compositions of microbial communities in the urban atmosphere.

Characteristic Changes of Bioaerosols in Beijing and Tsogt-Ovoo During Dust Events

Dust events moving at high altitudes by westerly wind can transport aerosols from Asian deserts to eastern Asia deposition areas such as China. Aerosols do not include only mineral particles but also microbial particles, which are called bioaerosols, and impact the ecosystem and air environment of the deposition area. For identifying the airborne microbial communities transported from the source area to the deposition area, bioaerosol samples were collected in the typical source region (Tsogt-Ovoo in Gobi deserts) and the deposition region (Beijing in Chinese industrial area) during dust events and non-dust days and the sampling sites were compared. The microscopic observation using DAPI fluorescent techniques revealed that the concentration of bioaerosols increased during the dust events in both the source and deposition regions. For the community structures of airborne bacteria at both sites, the dust-event occurrences changed the structure of the bacterial community and increased the diversity of bacterial communities during dust events. Some specific bacterial populations, such as members of Bacteroidetes, dominated during dust events. There is the possibility that specific bacteria can be maintained for a longer time in the atmosphere and might be transported from the source area to the deposition area.

Vertical stratification of the air microbiome in the lower troposphere

The troposphere constitutes the final frontier of global ecosystem research due to technical challenges arising from its size, low biomass, and gaseous state. Using a vertical testing array comprising a meteorological tower and a research aircraft, we conducted synchronized measurements of meteorological parameters and airborne biomass (n = 480) in the vertical air column up to 3,500 m. The taxonomic analysis of metagenomic data revealed differing patterns of airborne microbial community composition with respect to time of day and height above ground. The temporal and spatial resolution of our study demonstrated that the diel cycle of airborne microorganisms is a ground-based phenomenon that is entirely absent at heights >1,000 m. In an integrated analysis combining meteorological and biological data, we demonstrate that atmospheric turbulence, identified by potential temperature and high-frequency three-component wind measurements, is the key driver of bioaerosol dynamics in the lower troposphere. Multivariate regression analysis shows that at least 50% of identified airborne microbial taxa (n = ∼10,000) are associated with either ground or height, allowing for an understanding of dispersal patterns of microbial taxa in the vertical air column. Due to the interconnectedness of atmospheric turbulence and temperature, the dynamics of microbial dispersal are likely to be impacted by rising global temperatures, thereby also affecting ecosystems on the planetary surface.

Relationships between airborne microbial community diversity, heating supply patterns and particulate matter properties

Airborne microbes play critical roles in atmospheric ecology and human health, while the connections of microbial community with anthropic activity, such as heating supply patterns and chemical compositions of particulate matter (PM), remain unclear. The present study demonstrated that district heating supply regions exhibited higher microbial richness than non-district heating supply regions, and microbial richness in PM1 (aerodynamic diameter ≤ 1 µm) was significantly lower than that in PM10 (aerodynamic diameter ≤ 10 µm). Gram-positive bacteria were dominant, and Bacilli accounts for 85% of the noted bacteria. The total concentrations of heavy metals, polycyclic aromatic hydrocarbons (PAHs) and water-soluble ions increased with PM sizes. Heavy metals and PAHs in non-district heating supply regions showed significantly higher concentrations than that in district heating supply regions. Most of tested chemical compositions negatively contributed to microbial community diversity, except for Zn, Cr, Pyrene (Pyr), and Benzo[a]pyrene (Bap). The above results were also affected by heating supply patterns (district heating supply and non-district heating supply). There was a positive correlation between microbial community richness and •OH concentration, and microbial community richness decreased as PM specific surface area increased. This work reveals connections between the properties of PMs and the microbial community diversity with heating supply patterns, and gives novel insights to atmospheric health and carbon neutrality.

Diversity and Source of Airborne Microbial Communities at Differential Polluted Sites of Rome

Biogenic fraction of airborne PM10 which includes bacteria, viruses, fungi and pollens, has been proposed as one of the potential causes of the PM10 toxicity. The present study aimed to provide a comprehensive understanding of the microbial community variations associated to PM10, and their main local sources in the surrounding environment in three urban sites of Rome, characterized by differential pollution rate: green area, residential area and polluted area close to the traffic roads. We combined high-throughput amplicon sequencing of the bacterial 16S rRNA gene and the fungal internal transcribed spacer (ITS) region, with detailed chemical analysis of particulate matter sampled from air, paved road surfaces and leaf surfaces of Quercus ilex. Our results demonstrated that bacterial and fungal airborne communities were characterized by the highest alpha-diversity and grouped separately from epiphytic and road dust communities. The reconstruction of source-sink relationships revealed that the resuspension/deposition of road dust from traffic might contribute to the maximum magnitude of microbial exchanges. The relative abundance of extremotolerant microbes was found to be enhanced in epiphytic communities and was associated to a progressively increase of pollution levels as well as opportunistic human pathogenicity in fungal communities.

Microbiomes of air dust collected during the ground-based closed bioregenerative life support experiment "Lunar Palace 365"

BackgroundUnderstanding the dynamics of airborne microbial communities and antibiotic resistance genes (ARGs) in space life support systems is important because potential pathogens and antibiotic resistance pose a health risk to crew that can lead to mission failure. There have been few reports on the distribution patterns of microbiomes and ARGs in space life support systems. In particular, there have been no detailed investigations of microbiomes and/or antibiotic resistance based on molecular methods in long-term confined bioregenerative life support systems (BLSSs). Therefore, in the present study, we collected air dust samples from two crew shifts, different areas, and different time points in the "Lunar Palace 365" experiment. We evaluated microbial diversity, species composition, functional potential, and antibiotic resistance by combining cultivation-independent analyses (amplicon, shot-gun sequencing, and qPCR).ResultsWe found that the bacterial community diversity in the Lunar Palace1 (LP1) system was higher than that in a controlled environment but lower than that in an open environment. Personnel exchange led to significant differences in bacterial community diversity, and source tracking analysis revealed that most bacteria in the air derived from the cabin crew and plants, but no differences in microbial function or antibiotic resistance were observed. Thus, human presence had the strongest effect on the succession of microbial diversity in the BLSSs.ConclusionsOur results highlight that microbial diversity in BLSSs is heavily influenced by changes in crew and is unique from other open and controlled environments. Our findings can be used to help develop safe, enclosed BLSS that meet the requirements of human survival and habitation in outer space. In addition, our results can further enhance our understanding of the indoor air microbial community and effectively maintain a safe working and living environment, including plant growth.

The Response of Airborne Mycobiome to Dust Storms in the Eastern Mediterranean

Airborne microbial communities directly impact the health of humans, animals, plants, and receiving ecosystems. While airborne bacterial and fungal communities have been studied by both cultivation-based methods and metabarcoding surveys targeting specific molecular markers, fewer studies have used shotgun metagenomics to study the airborne mycobiome. We analyzed the diversity and relative abundance of fungi in nine airborne metagenomes collected on clear days (“background”) and during dust storms in the Eastern Mediterranean. The negative correlation between the relative abundance of fungal reads and the concentrations of atmospheric particulate matter having an aerodynamic diameter smaller than 10 μm (PM10) indicate that dust storms lower the proportion of fungi in the airborne microbiome, possibly due to the lower relative abundance of fungi in the dust storm source regions and/or more effective transport of bacteria by the dust. Airborne fungal community composition was altered by the dust storms, particularly those originated from Syria, which was enriched with xerophilic fungi. We reconstructed a high-quality fungal metagenome-assembled genome (MAG) from the order Cladosporiales, which include fungi known to adapt to environmental extremes commonly faced by airborne microbes. The negative correlation between the relative abundance of Cladosporiales MAG and PM10 concentrations indicate that its origin is dominated by local sources and likely includes the indoor environments found in the city.

RNA-Based Analysis Reveals High Diversity of Plant-Associated Active Fungi in the Atmosphere

Fungi are ubiquitous in nature; that is, they are present everywhere on the planet; understanding the active state and functional capacity of airborne microbes associated with health of human, animal, and plant is critical for biosafety management. Here, we firstly and directly proved that there were about 40% active fungi in the air via rRNA amplicon sequencing and imaging flow cytometry simultaneously. Amplicon sequencing analysis showed differences between structures of active and total fungal community; Ascomycota were dominant in the active community, while Basidiomycota have low transcriptional activity across all samples. Notably, plant pathogenic fungi were predominant in the air, and more than 50% were active, including not only several common plant pathogens but also biotrophic fungi (Erysiphe sp. and Microbotryum sp.) and host-specific pathogens, which were generally considered to be inactive after leaving the host. Putative plant pathogens of eight genera were found active across the sampling season, indicating their superior ability to obtain nutrients even in barren nutrient environments. Interestingly, we detected several potentially active unrecorded fungi in China (Diatrype prominens, Septofusidium herbarum, Pseudomicrostroma glucosiphilum, and Uromycladium tepperianum), which suggested that they spread over a long distance by air and may cause diseases under favorable conditions. Our results suggested that maintaining transmission in air is an essential feature of many fungi including plant pathogens regardless of being a biotrophic, hemibiotrophic, or necrotrophic group. Moreover, two potentially active human pathogens and one animal pathogen were captured, which indicated their potential risks. This study provided a new perspective for more comprehensive understanding of airborne fungi, including their multidimensional lifestyle, state, functioning, and potential pathogenic risk. It also laid the foundation for further prediction and management of airborne microbial communities, which would be of interest for public health and agriculture.

Seasonal Variability of the Airborne Eukaryotic Community Structure at a Coastal Site of the Central Mediterranean.

The atmosphere represents an underexplored temporary habitat for airborne microbial communities such as eukaryotes, whose taxonomic structure changes across different locations and/or regions as a function of both survival conditions and sources. A preliminary dataset on the seasonal dependence of the airborne eukaryotic community biodiversity, detected in PM10 samples collected from July 2018 to June 2019 at a coastal site representative of the Central Mediterranean, is provided in this study. Viridiplantae and Fungi were the most abundant eukaryotic kingdoms. Streptophyta was the prevailing Viridiplantae phylum, whilst Ascomycota and Basidiomycota were the prevailing Fungi phyla. Brassica and Panicum were the most abundant Streptophyta genera in winter and summer, respectively, whereas Olea was the most abundant genus in spring and autumn. With regards to Fungi, Botrytis and Colletotrichum were the most abundant Ascomycota genera, reaching the highest abundance in spring and summer, respectively, while Cryptococcus and Ustilago were the most abundant Basidiomycota genera, and reached the highest abundance in winter and spring, respectively. The genus community structure in the PM10 samples varied day-by-day, and mainly along with the seasons. The impact of long-range transported air masses on the same structure was also proven. Nevertheless, rather few genera were significantly correlated with meteorological parameters and PM10 mass concentrations. The PCoA plots and non-parametric Spearman’s rank-order correlation coefficients showed that the strongest correlations generally occurred between parameters reaching high abundances/values in the same season or PM10 sample. Moreover, the screening of potential pathogenic fungi allowed us to detect seven potential pathogenic genera in our PM10 samples. We also found that, with the exception of Panicum and Physcomitrella, all of the most abundant and pervasive identified Streptophyta genera could serve as potential sources of aeroallergens in the studied area.